Molding system with blow nozzle cleaning

ABSTRACT

A method of forming and filling a container with an end product. Accordingly to the method, a preform is located within a mold assembly that defines the shape of the container and a nozzle assembly is moved so as to engage with at least one of the preform and the mold assembly forming a liquid tight seal. The end product is injected into the preform to simultaneously form a container from the preform and fill the container with the end product. After forming and filling the container, the nozzle assembly, which was used to inject the end product, is disengaged from the preform and/or mold assembly. After the nozzle assembly is disengaged, the filled container is removed from the mold assembly and residual end product is purged from the nozzle assembly.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.13/721,934, filed on Dec. 20, 2012, which claims the benefit ofprovisional patent application No. 61/578,532, filed on Dec. 21, 2011,the entire contents of which are hereby incorporated by reference.

BACKGROUND

1 Field of the Invention

The present invention generally relates to the blow molding ofcontainers used for containing liquid and viscous products. Inparticular, the present system relates to blow molding systems where thecontainers are simultaneously blow molded and filled with the product.

2 Description of Related Art

Plastic containers are commonly used for the packaging of variousproducts, including liquid products and viscous product. One of the mostcommon forms of plastic container is the blow molded plastic container,which is often formed of a polyester material such as polyethyleneterephthalate (PET). Blow molded plastic containers are typically formedby placing a heated preform into a blow mold and then inflating thepreform with air until the preform contacts the interior surfaces of themold cavity, which define the final shape of the desired container. Oncethe inflated preform has been held against the interior surfaces of themold cavity by the pressure of the blow air for a length of timesufficient to “freeze” the plastic, the molded container is removed fromthe mold.

The molded containers then transported to the location where thecontainer will be filled with the intended product and labeled. This mayinclude the packaging and shipping of empty containers to a remotelocation or may involve the transfer of the containers to a localfacility where these final steps occur before the finished product isshipped to a retailer or end-user.

With the above method, blow molding and filling are distinct andseparate steps in the process of producing a product filled container. Anew process involves the use of the product itself in the blow moldingof the container. Instead of utilizing air as the blowing medium, thisnew process utilizes the liquid or viscous product that is to beretained within the container as the blowing medium. The container istherefore simultaneously blow molded and filled. As used herein, thistype of molding is referred to as liquid blow molding or hydraulicmolding.

In traditional blow molding, after the heated preform has been placed inthe mold cavity, a stretch rod is often advanced within the preform tolongitudinally stretch the preform before any significant radialexpansion of the preform is undertaken. The stretch rod will typicallyremain within the preform during radial expansion, and is retractedprior to removal of the resultant container.

One concern of hydraulic molding is the contamination of the preformsince product is immediately introduced into the preform during thehydraulic molding process. Since the stretch rod and blow nozzle are incontact with product used to hydraulically mold the container, there isa concern that residual product on the stretch rod or blow nozzle maybecome contaminated over time. Additionally, there is the possibilitythat residual product on the stretch rod or nozzle may be drip onto aheated preform, prior to dispensing of the hydraulic blowing medium, andthat contact of this residual product with the heated preform may resultin a local portion of the preform exhibiting defects after hydraulicmolding. One possible defect is a cosmetic discoloration of theresultant container. Another, more significant defect is that the moldedcontainer may experience blow out, wherein a hole is formed in thecontainer during the hydraulic molding process, resulting in thehydraulic blowing medium coming into contact with the interior surfacesof the mold and requiring extensive cleaning of the mold cavity. Ahydraulic molding machine would obviously experience significant downtime during the resultant cleaning process.

SUMMARY

In satisfying the above need, as well as overcoming the enumerateddrawbacks and other limitations of the related art, in one aspect thepresent invention provides a method of forming and filling a containerwith an end product. The method includes locating a heated preformwithin a mold assembly that defines the shape of the container, engaginga portion of a blow nozzle assembly with the preform, introducing theend product into the preform under pressure to simultaneously form thecontainer from the preform and fill the container with the end product,disengaging the portion of the blow nozzle assembly from the preformafter forming of the container, removing the filled container from themold assembly, and discharging and directing a stream of cleaning mediumtoward the blow nozzle assembly after the disengaging step, wherebyresidual end product is removed from the blow nozzle assembly.

In another aspect, the purging step includes directing a stream ofcleaning medium towards the nozzle assembly.

In further aspect, the step of directing the stream of cleaning mediumis performed on an intermittent basis.

In an additional aspect, the step of directing the stream of cleaningmedium includes directing one of a gas and liquid towards the nozzleassembly.

In another aspect, the step of directing the stream of cleaning mediumincludes directing one of air, nitrogen and CO₂ towards the nozzleassembly.

In still another aspect, the step of directing the stream of cleaningmedium includes directing a sanitizing agent towards the nozzleassembly.

In yet a further aspect, the step of injecting the end product includesthe step of injection one of a viscous material and a liquid.

In an additional aspect, the purging step is performed after theremoving step.

In yet another aspect, the purging step is performed before a furtherstep of locating another preform within the mold assembly.

In a further aspect, the purging step includes the step ofcircumferentially moving the mold assembly about a molding station andradially outwardly directing a stream of cleaning medium towards thenozzle assembly.

In still a further aspect, the purging step includes the step ofcircumferentially moving a blow-off nozzle with the mold assembly anddirecting the stream of cleaning medium from the blow-off nozzle.

In an additional aspect, the purging step includes the step ofcircumferentially moving the mold assembly while maintaining a blow-offnozzle stationary and directing the stream of cleaning medium from theblow-off nozzle.

In another aspect, the purging step includes the step of sequentiallydischarging different agents towards the nozzle assembly.

In a further aspect, one of the different agents is a rinsing agentdischarged after another of the different agents.

In an additional aspect, the step of sequentially discharging thedifferent agents includes discharging the different agents through acommon nozzle.

In still another aspect, the method further includes the step ofcollecting the residual end product after the purging step.

In yet a further aspect, the method of forming and filling the containeris a hydraulic blow molding process.

Further objects, features and advantages of this invention will becomereadily apparent to persons skilled in the art after a review of thefollowing description, with reference to the drawings and claims thatare appended to and form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematic illustration of a hydraulic blow molding systemincorporating the principles of the present invention;

FIG. 2 is a radially inward schematic view of a blow-off nozzle at onemolding station of the system seen in FIG. 1; and

FIG. 3 is a side schematic view of the blow-off nozzle and moldingstation seen in FIG. 2.

DETAILED DESCRIPTION

Referring now to the drawings, a hydraulic blow molding system embodyingthe principles of the present invention is generally illustrated in FIG.1 and designated at 10. As its primary components, the system 10includes an oven or heating station 12, a transfer station 14 and ahydraulic blow molding station 16. Additionally, the system 10 includesan in-feed station 18 for introducing preforms 20 into the oven 12 andan out-feed station 22 for removing formed and filled containers 24 fromthe hydraulic blow molding station 16.

Generally, preforms 20 are provided to the system 10 at the in-feedstation 18 by way of a rail or other transport mechanism 26. Thepreforms 20 are then individually loaded onto a conveyor 28, whichtransports the preforms 20 through the oven 12 and the transfer station14, and finally to a mold loading station 30. To secure the preforms 20on the conveyor 28, the conveyor may utilize carrier or spindleassemblies (not shown) that are connected to or supported by theconveyor 28.

The oven 12 includes a plurality of heaters 38 spaced along the lengthof the oven 12. The heaters 38 heat the material of the preforms 20 to apoint where the preforms 20 are susceptible to hydraulic blow molding.

From the oven 12, the heated preforms 20 are transferred by the transferstation 14 to the hydraulic blow molding station 16. Variousconfigurations can be envisioned for the transfer station 14. In theillustrated configuration, the transfer station 14 utilizes a primarytransfer wheel 46 that is coupled to the conveyor 28 to receive thepreforms from the oven 12. A secondary transfer wheel 48 is also used,in conjunction with the primary transfer wheel 46, to position andfacilitate transferring of the heated preforms 20 into the mold cavities32 at the mold loading station 30.

At the mold loading station 30, each preform 20 is removed from itscarrier assembly and placed within a mold cavity 32. A slide actuator orrobotic arm (not shown) may be used to facilitate the transfer of thepreforms 20 from the conveyor 28 into the mold cavities 32. Since suchtransfer mechanisms are known in the field of blow molding, furtherdetails of these mechanisms are not described herein.

Each mold cavity 32 is defined by interior surfaces 33 of opposing moldhalves 34 of a mold assembly 36, and multiple mold assemblies 36 areprovided at the hydraulic molding station 16. However, the actual numberof mold assemblies 36 at the hydraulic molding station 16 can and willvary depending on the specific design of the system 10 and the hydraulicmolding station 16. For example, in the rotary-style molding station 16generally seen in FIG. 1, the number of mold assemblies 36 may rangeanywhere from four to forty, or even more.

Once the heated preform 20 is positioned in the mold cavity 32, anactuator (not shown) closes the mold halves 34 about the heated preform20, thereby entrapping the heated preform within the mold assembly 36. Anozzle assembly 40, seen in FIGS. 2 and 3, is brought into sealingengagement with the finish (the threaded end portion) of the preform 20by an actuator (not shown). A stretch rod 42 may then be extended byanother actuator (not shown) through the nozzle assembly 40 and into thepreform 20. During extension, the stretch rod 42 engages the closed endof the preform 20 and axially elongates the preform 20. Simultaneouslywith, or subsequent to, actuation of the stretch rod 40, a hydraulicblowing medium 44 is introduced under pressure, through the nozzleassembly 40, into the preform 20. The pressure of the hydraulic blowingmedium 44 causes the preform 20 to radially expand until it is forcedinto conformity with the interior surfaces 33 of the mold cavity 32,thereby molding the preform 20 substantially into the final shape of thecontainer 24. Since the molding process of the system 10 is a hydraulicmolding process, the hydraulic blowing medium 44 is the actual liquid orviscous product (a non-gaseous product) that is to be packaged withinthe resulting container 24. To facilitate this process, the blowingmedium 44 is provided from a product source 46 that is coupled to thenozzle assembly 40. Accordingly, the container 24 is simultaneouslyformed and filled.

After an appropriate time in contact with the interior surfaces 33 ofthe mold cavity 32, the mold halves 34 are opened and the formed andfilled container 24 is removed from the mold assembly 36 at the out-feedstation 22. The transfer of the formed and filled container 24 from themold assembly 36 at the out-feed station 22 is performed by anothertransfer mechanism, such as a robotic arm or slide actuator. Again, suchtransfer mechanisms are known in the blow molding industry and need notbe further discussed herein.

From the out-feed station 22, the formed and filled container 24 istransferred to a sealing/capping station (not shown) where a seal, a capor both are applied. At this point, the filled and capped container 24may be subsequently transferred to a labeling station (not shown) wherelabeling is applied.

Because the preform 20 is hydraulically molded with a blowing medium 44that is in a liquid or viscous form (a non-gaseous form), it is possiblethat a residual amount of the hydraulic blowing medium 44 will remain onsome of the components in the blow molding station 16. For example, aresidual amount of the hydraulic blowing medium 44 may be found on thenozzle assembly 40 and the stretch rod 42, particularly where thestretch rod 42 was extended into the preform 20 while the hydraulicblowing medium 44 was being forced into the preform 20. As previouslynoted, it is possible that some residual blowing medium 44 might becomecontaminated and, if it is introduction into the preform 20 during asubsequent blowing sequence, it might result in contamination of theproduct in the container 24. Also as previously noted, the residualblowing medium may be at a different temperature than the actualhydraulic blowing medium 44. If the residual blowing medium happens tocontact the heated preform 20 prior to the introduction of the actualblowing medium 44, it is possible that the cooler residual blowingmedium could affect the thermal properties of the preform 20 and thesubsequent molding of the container 24. As an example, the effect may bea cosmetic defect in the clarity of the container or, more drastically,a hole formed in the expanding preform through which the hydraulicblowing medium 44 escapes.

To reduce the risk of contamination of the product and the formation ofdefects on the resultant container 24, a system 10 incorporating theprinciples of the present invention includes a blow-off system 48 forremoving/cleaning residual hydraulic blowing medium from variouscomponents of the system 10. Generally, the blow-off system 48 employs ablow-off nozzle 50 associated with each of the mold assemblies 36. Theblow-off nozzle 50 delivers a stream or blast, designated at 52, of acleaning medium across the various components at risk of having residualblowing medium thereon. Accordingly, the blow-off nozzle 50 directs thestream 52 across at least the nozzle assembly 40 and any associatedcomponents, including the stretch rod 42, a seal pin (not designated),portions of the mold assemblies 36 and other components.

In a preferred embodiment, at least one blow-off nozzle 50 is associatedwith each mold assembly 36. The blow-off nozzle 50 may be fixed inlocation relative to the mold assembly 36 or it may articulate toeffectuate cleaning/removal. In a rotary hydraulic molding station 16,such as that seen in FIG. 1, the blow-off nozzle 50 will preferablyrotate with its associated mold assembly 36, but stay a fixedrelationship relative to the mold assembly. Alternatively, one or morenon-rotating blow-off nozzles 50 could be provided so that, duringoperation of the rotary hydraulic molding station 16, the blow-offnozzle 50 does not rotate, but is stationarily fixed while the moldassemblies 36 are rotated past the blow-off nozzle 50 to effectuatecleaning and removal of any residual hydraulic blowing medium. In anin-line molding station (not shown) is another configuration, and inthat configuration, the blow-off nozzles 50 will also remain stationary.

Regardless of the embodiment, each provided blow-off nozzle 50 iscoupled to a source of the cleaning medium, which may be pressurized. InFIG. 3, the source of cleaning medium is generally designated at 54.Preferably, the cleaning medium is provided in a sterilized gas form,such as but not limited to air, nitrogen or CO₂. Alternatively, thecleaning medium may include or be a sterilizing agent, such as hydrogenperoxide, etc. Where a sterilizing agent is used, the application of thesterilizing agent may additionally be followed by the application of arinsing agent, which may be the sterilized gas mentioned above. In thislatter embodiment, the sterilizing agent and rinsing agents may beprovide sequentially from the same blow-off nozzle, or may be providedfrom separate blow-off nozzles, each respectively coupled to one of thesterilizing/rinsing agent sources.

In the rotary hydraulic molding station 16 of the figures, the blow-offnozzles 50 are directed radially outward of the hydraulic moldingstation 16. Directing the blow-off nozzles 50 in this manner ensuresthat residual blowing medium, when cleaned from the components of thestation 16, is not further dispersed onto other components of themolding station 16. In order to further limit inadvertent spraying orfurther contamination of other portions of the system 10, the removaland cleaning of residual hydraulic blowing medium from the variouscomponents occurs during only a portion of the hydraulic molding cycle.More specifically, the removal/cleaning of the residual hydraulicblowing medium occurs after a filled and formed container 24 has beenremoved from a mold assembly 36, but before the next preform 20 isplaced in that mold assembly 36.

Immediately after a filled container 24 has been removed from the moldassembly 36, the mold halves 34 are open and the nozzle assembly 40 isspaced apart therefrom. During the time from the removal of the filledcontainer 24 until the introduction of the next preform 20 therein, thestream 52 of cleaning medium is projected from the blow-off nozzle 50 soas to “air” wash the component at which it is directed. The force of thestream 52 is of sufficient strength such that any residual hydraulicblow medium on the subject components is completely and effectivelydislodged and directed to a collection unit 56.

The collection unit 56 can take any one of a variety of forms so long asit effectively captures the residual hydraulic blowing medium. In asimple construction, the collection unit 56 may include a collectionshield 58 onto which the residual hydraulic blowing medium is directed.Such a collection shield 58 may be oriented in an upright manner so thatonce on the shield 58, the residual hydraulic blowing medium travelsdownward under the influence of gravity, along the shield 58, and isdirected into a collection reservoir 60 in the base of the collectionunit 54. The shield 58 itself may have a variety of shapes and formsincluding being formed of a single flat-panel, a series of angled flatpanels, or as a curved panel.

Where blow-off nozzles 50 are associated with each of the moldassemblies 36, a valve 62 controls intermittent providing of thecleaning medium. The valve 62 may be operated such that the cleaningmedium is only discharged through the blow-off nozzle 50 during the timewhen the nozzle assembly 40 is disengaged from the mold assembly 36, thefilled container 24 has been removed from the mold assembly 36, andbefore the next preform 20 is placed therein. Operation of the blow-offsystem 48 is therefore anticipated as occurring in the latter stages ofrotation of the rotary hydraulic molding station 16, generally betweenthe out-feed station 22 and the mold loading station 30. In an in-linehydraulic molding system, this would occur after take-out of the filledcontainer 24 and prior to introduction of the next preform 20. Operationof the valve 62 can therefore be controlled by the electronic controller(not shown) operating the system 10, which may be wireless, to ensureprecise actuation and timing of the delivery of the stream 52 ofcleaning medium.

As a person skilled in the art will readily appreciate, the abovedescription is meant as an illustration of implementation of theprinciples this invention. This description is not intended to limit thescope or application of this invention in that the invention issusceptible to modification, variation and change, without departingfrom spirit of this invention, as defined in the following claims.

We claim:
 1. A method of forming and filling a container with an endproduct, the method comprising steps of: locating a preform within amold assembly defining a shape of the container; engaging a nozzleassembly with at least one of the preform and the mold assembly to forma liquid tight seal; injecting the end product under pressure from thenozzle assembly into the preform to simultaneously form a container fromthe preform and fill the container with the end product; disengaging thenozzle assembly from at least one of the container and the mold assemblyafter forming of the container; removing the container filled with theend product from the mold assembly; and after both disengaging of thenozzle assembly from at least one of the container and the mold assemblyand removing of the container filled with end product from the moldassembly, purging residual end product from the nozzle assembly, thepurging of the residual end product including circumferentially rotatinga blow-off nozzle with the mold assembly with the blow-off nozzle beingpositioned radially inward of the mold assembly and oriented to direct astream of purging medium radially outward and toward the nozzleassembly.
 2. The method of claim 1, wherein the step of directing thestream of purging medium is performed on an intermittent basis.
 3. Themethod of claim 1, wherein the step of directing the stream of purgingmedium includes directing one of a gas and liquid towards the nozzleassembly.
 4. The method of claim 1, wherein the step of directing thestream of purging medium includes directing one of air, nitrogen, andCO₂ towards the nozzle assembly.
 5. The method of claim 1, wherein thestep of directing the stream of purging medium includes directing asanitizing agent towards the nozzle assembly.
 6. The method of claim 1,wherein the step of injecting the end product includes the step ofinjection one of a viscous material and a liquid.
 7. The method of claim1, wherein the purging step is performed before a further step oflocating another preform within the mold assembly.
 8. The method ofclaim 1, further comprising the step of collecting the residual endproduct after the purging step.
 9. The method of claim 1, where themethod of forming and filling the container is a hydraulic blow moldingprocess.
 10. A method of forming and filling a container with an endproduct, the method comprising steps of: locating a preform within amold assembly defining a shape of the container; engaging a nozzleassembly with at least one of the preform and the mold assembly to forma liquid tight seal; injecting the end product under pressure from thenozzle assembly into the preform to simultaneously form a container fromthe preform and fill the container with the end product; disengaging thenozzle assembly from at least one of the container and the mold assemblyafter forming of the container; removing the container filled with theend product from the mold assembly; and after both disengaging of thenozzle assembly from at least one of the container and the mold assemblyand removing of the container filled with end product from the moldassembly, purging residual end product from the nozzle assembly, thepurging of the residual end product including circumferentially rotatinga blow-off nozzle with the mold assembly with the blow-off nozzle beingpositioned radially inward of the mold assembly and oriented to direct astream of purging medium radially outward, wherein the purging stepincludes the step of sequentially discharging different agents towardsthe nozzle assembly.
 11. The method of claim 10, wherein one of thedifferent agents is a rinsing agent discharged after another of thedifferent agents.
 12. The method of claim 10, wherein the step ofsequentially discharging the different agents includes discharging thedifferent agents through a common nozzle.